The hepatitis B vaccine is recommended for all adults aged 19–59, and for adults 60 and older who have risk factors. The newer two-dose series (Heplisav-B) can be completed in about a month, while older versions use three shots. It prevents a lifelong liver infection CDC, 2022.
treatable, not curable
testing, not symptoms, decides
| Item | Value |
|---|---|
| Curable? | managed — treatable, not curable |
| Tested by | exam + lab |
| Often | no symptoms |
| If you may have it | get tested — testing, not symptoms, decides |
Why hepatitis B is worth preventing
Hepatitis B is a vaccine-preventable liver infection caused by the hepatitis B virus (HBV). It spreads when blood, semen, or other body fluids from an infected person enter someone who isn't immune, through sex, sharing needles or injection equipment, and from a pregnant person to the baby at birth. It is not spread by sneezing, coughing, hugging, or sharing food, water, or utensils CDC.
The infection has two faces. Acute hepatitis B is a short-term illness in the first six months after exposure, and many adults have mild or no symptoms and clear it on their own. Chronic hepatitis B lasts beyond six months, can be lifelong, and quietly scars the liver over decades. Which path you take depends mostly on age at infection. Caught in adulthood, HBV becomes chronic in under 5% of people; caught in infancy it becomes lifelong in about 90%, which is why newborn protection is so urgent.
Acute reports have held roughly steady at about 2,200 a year between 2020 and 2023, but that number badly understates the problem, since hundreds of thousands more Americans live with undiagnosed chronic infection CDC AtlasPlus, 2023. Chronic HBV often causes no symptoms for years, so it's easy to carry and pass on without knowing. For more on that silent course, see our overview of hepatitis b and c.
How to prevent hepatitis B
A handful of proven prevention tools stack together. Vaccination is the foundation; condoms, testing, and sterile injection practices fill the gaps.
Vaccination — the best protection
The Advisory Committee on Immunization Practices (ACIP) recommends the hepatitis B vaccine for all adults aged 19 through 59, and for adults 60 and older who have risk factors, including new sex partners, a partner with HBV, injection drug use, or certain medical conditions. If you're 60 or over without risk factors, you can still choose to be vaccinated. The vaccine teaches your immune system to make anti-HBs antibodies, so a real exposure is neutralized before infection takes hold.
Getting vaccinated as an adult is routine and low-drama. The newer two-dose product is given a month apart, and you don't need a blood test before starting unless you have a specific reason to check immunity. Soreness at the injection site is the most common side effect. If you're unsure whether you were vaccinated as a child or have already recovered from HBV, a quick serologic panel sorts it out.
Post-exposure prophylaxis
If you've had a defined exposure to someone who is HBsAg-positive, such as a needlestick, a sexual exposure, or a household exposure, and you're not already immune, you'll want post-exposure prophylaxis: hepatitis B immune globulin (HBIG) plus the vaccine, started as soon as possible and ideally within 24 hours CDC STI Tx Guidelines. HBIG gives immediate, borrowed antibodies while the vaccine builds your own. Timing matters, so go to a clinic or urgent care the same day. For how soon different exposures show up on tests, see when to test after exposure.
Condoms and their limits
Condoms used every time lower the risk of sexually transmitted HBV by blocking contact with semen and blood. They're a real but partial layer of protection. They don't cover every site of potential fluid contact, they can slip or break, and they do nothing about non-sexual routes like shared injection equipment. Treat condoms as risk-reduction that complements the vaccine, which gives durable protection regardless of exposure.
Safer injection and not sharing equipment
HBV is efficiently transmitted through blood, so never share needles, syringes, or other injection equipment, and don't share items that may carry traces of blood such as razors or toothbrushes. People who inject drugs are among those ACIP specifically recommends for vaccination.
Testing as prevention
Testing catches infection that has no symptoms before it spreads or damages the liver. CDC now recommends that all adults aged 18 and older be screened for hepatitis B at least once in their lifetime, and that pregnant people be screened each pregnancy CDC, 2023.
The standard is a triple serologic panel that answers three different questions at once:
- HBsAg (hepatitis B surface antigen) — a positive result means active infection right now, acute or chronic.
- Anti-HBs (surface antibody) — a positive result means immunity, either from vaccination or from recovering from a past infection.
- Total anti-HBc (core antibody) — a marker of past or current natural infection (it does not appear from vaccination).
Read together, these three tell you whether you're susceptible and should be vaccinated, already immune, or currently infected CDC diagnosis. If you've had a recent risky exposure, antibodies and antigen take time to become detectable, so read about the hepatitis b window period and how soon to test before you test, so an early-negative result doesn't give you false reassurance. You can get tested at most clinics with a single blood draw.
Where PrEP and DoxyPEP fit in
HIV PrEP and DoxyPEP get a lot of attention for other sexually transmitted infections, but neither prevents hepatitis B. HBV has its own dedicated vaccine, which is more effective for this virus than any pill-based strategy. There is no DoxyPEP equivalent for HBV. Vaccination plus HBIG after a known exposure is the established preventive toolkit here.
Special situation: pregnancy and newborns
Hepatitis B can pass from a pregnant person to the baby around the time of birth, the most common way young children become infected, which is why every pregnancy is screened for HBsAg CDC perinatal. An infant infected at birth has about a 90% chance of developing lifelong infection, far higher than the roughly 95% of adults who clear it, so newborn prevention is the highest-yield step in the whole disease.
The protection is dramatic. Giving the newborn both the vaccine and HBIG within 12 hours of birth drops transmission to about 3.6%, versus 11.6% with the vaccine alone; adding an antiviral for high-viral-load mothers lowers it further to under 2% network meta-analysis. Every newborn already gets the hepatitis B vaccine at birth, and a baby born to an HBsAg-positive parent also gets HBIG.
Putting it together
For most adults the plan is simple. Get the vaccine if you haven't, confirm your status with a one-time screening panel, and use condoms and sterile injection practices to cover the routes between you and immunity. Hepatitis B is common and manageable. Clinics handle it every day, and it says nothing about you as a person.
| Prevention tool | What it does | Best for |
|---|---|---|
| Hepatitis B vaccine | Builds durable, exposure-independent immunity | All adults 19–59; 60+ with risk factors |
| Condoms (every time) | Lower sexual transmission risk | Anyone not yet immune; partial protection |
| Lifetime screening panel | Finds silent infection and confirms immunity | All adults 18+, once |
| HBIG + vaccine (PEP) | Immediate plus building protection after exposure | Non-immune people exposed to an HBsAg-positive source |
| Not sharing injection equipment | Blocks blood-borne transmission | People who inject drugs |
When to see a clinician
See a clinician promptly if you've had a possible exposure to someone with hepatitis B and aren't sure you're immune, since post-exposure prophylaxis is time-sensitive. Also get checked if you have yellowing skin or eyes, dark urine, persistent fatigue, or right-upper-abdominal pain, or if you're starting chemotherapy or immune-suppressing medication, which can trigger hepatitis b reactivation in people who carry the virus. Anyone who's never been screened should ask for the one-time panel at their next visit.